Scenarios
1. Introduction
Scenarios are narratives of possible futures, depicting divergent visions of what the future may hold and providing insights when evaluated of potential outcomes for nature and society.
Scenarios capture different decisions and policy options being considered by multiple partners working and living in a region.
Scenarios are then translated by models into consequences for nature, nature’s benefits to people and quality of life (IPBES 2016).
Current drives of biodiversity loss and environmental degradation have promoted the evaluation of multiple scenarios that are usually of global scale concern (top-down approaches), such as climate change and land cover and land use change. Multilateral agencies have developed global narratives to help inform global targets and national policies.
In contrast with this top-down approach, participatory scenarios (bottom-up approaches) emerge to respond to local communities’ specific needs, realities and expectations. Aligning and integrating top-down and bottom-up approaches, that is plausible global and local narratives and their interactions, is an ongoing challenge.
There is also a trend to create explicit narratives for biodiversity and ecosystem services or at least include their story-lines within scenario evaluation.
Before describing global, participatory and narrative for biodiversity and ecossytem services, let’s present four different types of scenarios proposed by IPBES (2016) (Figure below). Although these types of scenarios are proposed under the umbrella of top-down approaches, it can also help participatory scenario planning.
Exploratory scenarios examine a range of plausible futures, contributing to high level-level problem identification and agenda setting. For instance, socio-economic scenarios are a common starting point to explore plausible futures for biodiversity, ecosystem services and human well-being.
Intervention scenarios evaluate alternative policy or management, contributing to policy design and implementation. There are two classes of intervention scenario:
Target-seeking scenarios: there is agreement on a common target but there are alternative pathways to get there (e.g., exploring structural changes in production and consumption to reduce biodiversity loss, Netherlands Environmental Assessment Agency 2010).
Policy-screening scenarios: evaluate several available policy instruments in moving towards specific targets or goals.
Retrospective policy evaluation (also known as “ex-post evaluation”), the observed trajectory of a policy implemented in the past is compared to scenarios that would have achieved the intended target.
Note: The Integrated Assessment Modeling Consortium has coordinated several processes to collect quantitative integrated assessment scenarios from the research community.
2. Drivers of change
This section is under construction!
Climate change Land-cover and land use change
3. Global scenarios
“Scenarios capture different policy options being considered by decision makers, which are then translated by models into consequences for nature, nature’s benefits to people and quality of life” (IPBES 2016).
IPBES (2016) described four different types of scenarios (Table below) and proposes an approach to use scenarios and models to assess uncertainties in future outcomes required to inform the four stages of the policy cycle.
Categories of scenario types as described by IPBES (2016)
| Scenario type | Aim | Summary | Examples |
| Exploratory (descriptive) | To support agenda setting | Examines a range of plausible futures, based on potential trajectories of drivers – either indirect (e.g., socio-political, economic and technological factors) or direct (e.g., habitat conversion and climate change) | Millennium Ecosystem Assessment |
| Target-seeking (normative) | To support policy design | It examines the viability and effectiveness of alternative pathways to the desired outcome. | Roads from Rio +20: Pathways to achieve global sustainability goals by 2020 |
| Policy screening (ex-ante) | To support implementation | A policy, or set of policies, is applied and an assessment of how the policy modifies the future is carried out | Rethinking Global Biodiversity Strategies (Ten Brink et al 2010)
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| Retrospective policy evaluation (ex-post) | To support policy review |
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3.1. Exploratory scenarios
“Exploratory scenarios” examine a range of plausible futures, contributing to high level-level problem identification and agenda setting. For instance, socio-economic scenarios are a common starting point to explore plausible futures for biodiversity, ecosystem services, and human well-being (Table below).
Global Socio-Economic Scenarios.
| Name | Scenarios |
| Share Socio-economic Pathways (SSPs, IPCC 2021, see also description here) | Share Socioeconomic Pathways (SSPs)
Representative Concentration Pathways (RCPs, CMIP6, earlier climate scenarios) Moss et al. (2010), van Vuuren et al. (2011), Climate Change (2021); O’Neill et al. (2016); Meinshause et al. (2020).
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| The Millennium Ecosystem Assessment, 2005 |
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For example, Shared Socioeconomic Pathways (SSPs) are based on five plausible narratives describing alternative socio-economic developments (Riahi et al. 2017). SSPs include a range of scenarios drivers such as population, economic growth and urbanization, further use to develop integrated scenarios (baseline and mitigation), including energy systems, land-use change (Popp et al. 2017), air pollutants, greenhouse gas emissions and atmospheric concentrations (Riahi et al. 2017). Within these, SSP 2 “Middle of the Road” SSP 2 describes a world in which the human population peaks at 9.4 billion by 2070 and economic growth is moderate and uneven, while globalization continues with slow socio-economic convergence between countries.
How biodiversity has been assessed within global scenarios?
Controlling future changes of land use
Recent research has used SSPs as a basis to assess single action vs. combined action scenarios for biodiversity recovery in the coming century (Leclère et al. 2020). Leclère et al. (2020) found that global terrestrial biodiversity trends caused by habitat conversion could be reversed if action was immediate, and of unprecedented ambition and coordination. This would be possible while still being consistent with the broader sustainability agenda, such as provisioning the food for the growing human population. The trends varied across the six biodiversity indicators they chose that were selected for their ability to project biodiversity metrics regionally and globally under various scenarios of spatially explicit future changes in land use. Their projections considered only the effect of future changes in land use, and did not account for future changes in other threats to biodiversity (for example, climate change, biological invasions or hunting).
Integrating regional climate change-biodiversity feedbacks
Recent research calls for more realistic scenarios that integrate regional climate change-biodiversity feedbacks (Cabral et al. 2023). One recent example is provided by Mori et al. (2021) who assessed the benefits of climate mitigation on global tree biodiversity (persistence and changes in distribution due to range shifts), and the benefits this would have for diversity dependent primary productivity and carbon storage by forests. They found that, in many biomes, climate change mitigation could substantially reduce the global loss of tree diversity that would otherwise be expected to result from an unabated climate change. This, in turn, is expected to reduce the loss of productivity that would otherwise be expected to result from biodiversity loss. Climate change mitigation is estimated to curtail productivity losses by approximately 9–39% compared with the baseline scenario of unabated warming. The alleviated loss of tree diversity and the resultant conservation of biodiversity-dependent productivity are especially substantial in colder and drier biomes compared with warmer and wetter biomes, probably because species in these biomes are often close to the edge of their climatic niche.
Reducing the adverse impacts of climate change on species in ecosystems is important, as they serve as a massive sink and storehouse of carbon, thereby contributing to climate stabilization (the desirable pathway to stabilizing feedback between climate change mitigation and biodiversity conservation. This scenario analysis reveals a triple win for climate, nature, and society by simultaneously protecting and leveraging the ecosystem benefits contributed by the biodiversity of the world’s forests.
3.2. Target seeking scenarios
Global commitments to the GBF to protect 30% of land by 2030 present an opportunity to slow rates of biodiversity loss by protecting critical habitat and reducing extinction risk. Let’s see a couple of examples in this direction.
This section is under construction!
Evaluating 30 x 30 conservation Scenarios for Canada
Eckert et al. (2023) explored a range of 30×30 conservation scenarios for Canada that varied the dimension of biodiversity prioritized (i.e. taxonomic groups, species-at-risk, biodiversity facets) and how protection is coordinated (transnational, national, or regional approaches) to test which decisions influence our ability to capture biodiversity in spatial planning.
They evaluated how well each scenario captures biodiversity using scalable indicators while accounting for climate change, data bias, and uncertainty. They used spatial prioritization to test whether prioritizing different dimensions of biodiversity versus prioritizing at different spatial scales matters more for 30×30 biodiversity outcomes (Figure below).
They first built species distribution models to project the current and future ranges of all Canadian terrestrial vertebrates, plants, and butterflies. To incorporate climate change, they down-weighted future projections to account for uncertainty and to prioritize “win-win” areas of overlap between current and future ranges. Next, they designed 30×30 expansion scenarios that varied the dimension of biodiversity (i.e., taxa, species at-risk, facets) to be prioritized and how well protection is coordinated spatially. Finally, to evaluate spatial prioritization scenarios, they quantify both the amount of biodiversity captured using weighted endemism as well as the number of species protected based on a modified Species Protection Index (SPI), where a species is considered protected when it reaches or exceeds its species-specific conservation target.
They found that only 15% of all terrestrial vertebrates, plants, and butterflies (representing only 6.6% of species-at-risk) are adequately represented in existing protected land in Canada. However, a nationally coordinated approach to 30×30 could protect 65% of all species representing 40% of all species-at-risk. How protection is coordinated has the largest impact, with regional approaches protecting up to 38% fewer species and 65% fewer species-at-risk, while the choice of biodiversity incurs much smaller trade-offs. These results demonstrate the potential of 30×30 planning in Canada while highlighting the critical importance of biodiversity-informed national strategies (Figure below).
Spatial prioritization for Quebec, Canada
The same analyses were applied to Quebec (Eckert et al. 2023b) in an analysis for the MELCCFP of the Quebec government. At the provincial level, spatial priorities for biodiversity can be clustered into four main geographic groups, although there are areas of high priority across the province (Figure below). High priority clusters include the southern region of the province including parts of Les Appalaches, Basses-terres du Saint-Laurent, Les Laurentides méridionales, Basses-terres de l’Abitibi as well as the area around Lac Saint Jean (Graben du Saguenay), the northern region including parts of Monts de Puvirnituq, Plateau de Salluit, Basses-terres de Puvirnituq, and Monts Torngat, and a mid-latitude region encompassing parts of Plateau de la Sainte-Marguerite and Massif du lac Magpie. These high priority areas contain a disproportionate amount of biodiversity and the establishment of new protected land in the identified 30x30 priority areas could enable the adequate protection of over 45% of Québec’s species. Furthermore, the expansion of protected land in these high priority areas could confer adequate protection for ~30% of all at- risk species, species which are largely under protected by existing protected areas. This represents a substantial gain from Québec’s current state of biodiversity conservation.
Given the predicted high impact of climate change on species ranges in Québec, the observed difference in current and future spatial priorities is expected (Figure below).
Future priorities under climate change tend to shift northward towards cooler regions where Québec’s biodiversity is expected to shift into. Low-latitude priority regions are still high priority areas in future scenarios given the extremely high species richness in southern Québec ecosystems and the persistence of that richness into the future despite climate change. We see areas on the east coast of James Bay come out as high and highest priority in all three scenarios (Figure below).
4. Participatory scenarios
This section is under construction! While large-scale/global scenarios provide good general guidance, and may help elicit some underlying linkages between social, demographic and economic features on the one side and ecosystem level changes on the other side, small-scale/local scenarios can be very useful for exploring possible futures at the community level. Participatory scenarios usually involve selected local or regional actors, recognized representatives of communities, and members with a certain expertise. They are most valuable for supporting community involvement, enabling local stewardship, and giving communities an opportunity to contribute to setting their own targets and imagine their own futures in view of conservation issues, local livelihoods and national policies.
5. Biodiversity and Ecosystem Services Scenarios
This section is under construction!
Global biodiversity scenarios (see Ferrier et al. 2016) are difficult to identify and are usually built using direct drivers of ecosystem change such as Climate Change (CC) and Land-Cover and Land-Use Change (LCLUC, see Titeux et al. 2016), known as model-based biodiversity scenarios (Pereira et al. 2010, Kim et al. 2018). For instance, Kim et al. (2018) argue that the role nature and biodiversity-specific policies in scenario storylines are limited, as follow: “...coarse spatial resolution, and land-use classes that are not sufficiently detailed to fully capture the response of biodiversity to land-use change”. This is exacerbated by the heterogeneity of models and their methodological approaches and the lack of harmonized metrics of biodiversity and ecosystem services (except for the global Land-Use Harmonization (LUH) project see Hurtt et al. 2020).
Ecosystem services scenarios (ESSs) are even more difficult to construct and have been explored under the Millennium Ecosystem Assessment, 2005 scenarios (Bennett et al. 2005). Thus, challenges remain in developing relevant global scenarios for biodiversity (Maurin et al. 2022) and ecosystem services (Rosa et al. 2019.)), although some initiatives have emerged to co-create positive futures for nature and people (Lundquist et al. 2021, IPBES 2023, Kim et al. 2023, Sarkki et al. 2023, O’Connor et al. 2021).
Intercomparison of biodiversity and ecosystem services models using harmonized scenarios (SSPs and RCPs; two major drivers: land use and climate, Kim et al. 2018) have shown important limitations to overcome.
Expected outcomes from scenarios depend strongly on the choice of biodiversity model used
Projected outcomes for biodiversity under different scenarios depend not only on the social and economic scenario but also on the choice of climate scenario and the type of biodiversity model used to project change (Thuiller et al. 2019). Biodiversity scenarios are not meant to predict the future state of a biodiversity variable precisely, but rather to project the range of possible futures to better understand uncertainties and alternative expectations for the future.
Accounting for climate scenarios, representative concentration pathways (e.g., RCPs), along with land-use scenarios, allows for an assessment of biodiversity change under a wide range of possible futures. Thuiller et al. (2019) stressed the importance of the choice of biodiversity models. There are different types of biodiversity models to consider, but statistical Species Distribution Models (SDMs), are particularly widespread. Thuiller et al. (2019) found that different algorithms could lead to substantial variability in expected outcomes and the uncertainty associated with them, which may override even the choice of RCPs. This issue was long recognized in climate sciences where it is no longer appropriate to show projected climatic trends from a single Global Climate Model (GCM). Rather, ensembles of climate trajectories are provided to users for scenario comparison via data portals (e.g., CMIP5).
The biodiversity modelling community needs to report and communicate the variability resulting from the different options in biodiversity models (e.g. SDMs, dispersal scenarios) and scenario-derived input data (e.g., RCP). Thuiller et al. (2019) urged that variabilities originating from modelling algorithms, input data, and external forces be assessed and reported for better to strengthen the science and improve the confidence in the scenario-based findings for decision-makers in exploring options for conservation action (e.g., placement of in situ measure and protected areas.
6. Workshop findings
GEO BON and Parks Canada convened a two-day workshop in Montreal (Oct 16-17, 2023) with primary knowledge holders from three main partners groups: GEO BON experts, regional experts and indigenous scholars and partners (e.g., Parks Canada, ECCC, Indigenous communities). Some of the main conclusions from this workshop were:
The IPBES (2016) framework explains how to combine models, scenarios and, weaving multiple knowledge systems to help partners working and living in the HJBL.
The Group on Earth Observations Biodiversity Observation Network (GEO BON) provides a framework to monitor biodiversity and ecosystem services and can guide the development and implementation of tools for monitoring. The Canadian Consortium for Arctic Data Interoperability (CCADI) provides ethically open, accessible, and comprehensive digital resources to the broadest possible audience of data users.
Existing initiatives in the area provide a firm foundation for future work. A bottom-up approach could support The Cree Geoportal as a main GeoHub and observatory for the HJBL. Other regional observatories could offer valuable operational experience in similar environments and challenges (e.g., The Alaska Arctic Observatory and Knowledge Hub, The Sustaining Arctic Observing Networks (SAON), The Pan-Arctic Observing System of Systems (Arctic PASSION), The Research Network Activities for Sustained Coordinated Observations of Arctic Change (RNA CoObs) that supports SAON).
BON-in-a-Box enables alignment of the stakeholder and rightsholder communities on priorities for biodiversity monitoring and the data and models needed to produce robust conclusions about the trends in different facets of biodiversity and ecosystem services. This focuses shared resources needed to execute those priorities and accelerates adoption of information about biodiversity change into decision support tools.
7. Guidance for action
1. Key areas
Create working groups to:
Support and enhance capabilities of the local observatories:
Deploy an information system that integrates observations, models and tools into reproducible and open workflows that respect FAIR and CARE principles (e.g. Bon in a Box):
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2. Exploratory scenarios
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3. Target seeking scenarios Coordinating efforts across spatial scales confirms the critical need to evaluate national strategies for reaching global targets (e.g., protecting 30% of Earth’s land by 2030, 30x30) (Eckert et al. 2023).
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